1. Field of the Invention
This invention is in the field of an electromagnetic water treatment device as disclosed in my U.S. Pat. No. 4,151,090 granted on Apr. 24, 1979, and my U.S. Pat. No. 4,148,731 granted on April 10, 1979.
This invention is in the field of liquid heaters, boilers and vaporizers which are provided with a cleaning means and in particular cleaning means in which pneumatic pressure for the purpose of separating suspended solids which collect at the bottom of the liquid heater or boiler.
This invention is in the field of testing the liquid suspension of solids and in improved electrical control circuits for such testing in order to initiate automatic blowdown of predetermined quantities of solids.
This invention also relates to low cost apparatus for the physical treatment of boiler water at elevated temperatures which includes as a critical step in such physical treatment the electromagnetic treatment of all incoming feed water to the boiler whereby suspended solids and dissolved solids in the water which is in an incipient state of precipitation can be safely removed physically by blowdown procedures in predetermined quantities and for predetermined times.
2. Description of the Prior Art
In the prior art of cleaning boilers by blowdown procedures water treating chemicals have been fed into the boiler and the treated water has been removed by blowdown devices, an example of said chemical treatment being Rivers U.S. Pat. No. 3,139,071. The chemical treatment in this patent requires the provision of a reservoir for the chemical, a pump, a filter, accurate records for the amounts employed and close supervision. Another example of a blowdown system employing chemicals to treat the water is found in Anderson U.S. Pat. No. 3,908,605. Anderson provides automatic operation and uses a conductivity sensor model which facilitates blowdown at low or at high pressures. Indeed, the Anderson system permits optional surface blow for removal of froth which accumulates in chemical treatment. One of the difficulties with the Anderson system is its high cost, despite the fact that the energy savings are significant. It is recognized that energy costs for fuel are very substantially affected by the scale thickness within the boiler. Tables and graphs provided by the EPA have demonstrated that 8% of the fuel bill is wasted, for a 100 horsepower boiler operating every day for the entire year at 85.cent. per gallon, oil cost would add $18,466.00 to the bill. If the scale thickness increases to 7/64" then the extra oil cost is $46,165.00. Faced with these fuel costs it is not at all surprising to find that substantial investments are made in chemicals for water treatment within the boiler, for devices to dose these chemicals and for personnel to carefully watch this treatment.
The present invention provides an advantage over the Anderson system in his U.S. Pat. No. 3,908,605 by changing the location of the probe to within the boiler as is done in the nuclear energy steam plants and by providing a novel external straight line sludge collector having an enlarged diameter, two to four times the diameter of the standard opening at the base of the boiler whereby the sludge removed by outside blowdown avoids excessive turbulence within the boiler following automatic blowdown procedures, causing resuspension of the sludge resulting from inner blowdown.
Other prior art is known for automatic blowdown. For example, Holdt U.S. Pat. No. 3,680,531 in which a monitoring system is used for repeating the sampling at fifteen minute intervals in an automatic blowdown system. The present invention distinguishes over this Holdt patent in providing controls for the electromagnetic unit and for the sensor probe on a common panel so that there can be assurance that all physical treatment systems are operative. This not only improves the efficiency of the system but lowers the cost. Two panels are more costly than a single panel. Electrical costs are cut because the rectifier circuit for 24 volt DC current energizes the probe for sensing total dissolved solids and also energizes the electromagnet in the electromagnetic water conditioning unit.
Courvoisier et al U.S. Pat. No. 3,552,189 granted Jan. 5, 1971, assigned to the French Atomic Energy Commission discloses a monitoring apparatus to detect the imminent danger of scale formation on a surface for transfer of heat between scale forming liquid and the liquid in the form of vapor before deposit has begun to form. Courvoisier et al points out that large boilers used in the atomic energy field are very expensive and it is essential that they remain efficient in order to prevent irreparable damage to the boiler as well as costly chemical or mechanical cleaning of the surface after scale has formed. Although Courvoisier et al are familiar with boiler systems for the prevention of scale they recognize that for desalination of sea water by distillation that the formation of salt deposits is one of the most important problems to be overcome. As stated by Courvoisier et al, "the deposits which are formed increase at such a high rate that, when a drop in efficiency is observed as a result of such deposits, it is already too late to modify the conditions of operation of the plant (temperature, concentration factor, hydrodynamic parameters). It is therefore necessary to stop production in order to carry out either chemical or mechanical cleaning of the surfaces." The present invention is useful for the same purposes of Courvoisier et al but relies upon electromagnetic treatment to prevent scale deposits from adhering to the metal surface and utilizes in combination with the electromagnetic treatment, particularly in applicant's prior application Ser. No. 153,219 filed May 27, 1980, now U.S. Pat. No. 4,288,323, an external sludge collector in the form of a straight pipe with a diameter about three times as great as the diameter of the standard opening at the bottom of the boiler. As a direct result of the electromagnetic treatment, the deposited salt is formed as a nonadhering mass and can readily be removed by automatic bottom blowdown procedure from a location outside of the boiler.
I am also aware of the patent to Dallimonti, granted Jan. 4, 1977, assigned to Honeywell, Inc. of Minneapolis, Minnesota, which relates to a console cathode-ray digital display and control system which is especially adapted for large municipal water, sewage and steam systems. These industrial plants and particularly those which are used for automatic energy and boiling water reactors are benefited by digital display and control consoles on which are mounted a number of individual process control instruments and read-out devices arranged for manipulation and monitoring by a human operator to achieve control over the process. The apparatus of the present invention is adapted for monitoring within the system of this Dallimonti patent.